Add renewal info to license expiration warning banner
### Overview The warning message we present when a license is expiring isn't particularly clear. We should make it more prescriptive and directive so customers understand what they need to do. ### Acceptance Criteria: * Add link to https://about.gitlab.com/pricing/licensing-faq/#self-managed-gitlab * Copy should say "Your license will expire in X days. For renewal instructions [view our Licensing and Subscription FAQ]."
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